PAIRING OP INSECTS. 231 



particularly since they do not swim so well " as to 

 bestar with their phosphorescent splendour the vast 

 surface of the ocean, and transform it into a sea of 

 flame," — a spectacle, continues Humboldt, " which 

 stamped upon my memory an ineffaceable impression, 

 and always excited fresh astonishment, although it 

 was renewed every night for months together. It 

 may be seen in every zone ; but those who have not 

 witnessed it within the tropics, and above all upon 

 the main ocean, can form but a very imperfect 

 conception of the grandeur of the phenomenon, 

 particularly if the spectator places himself in the 

 shrouds of a ship of the Hue, during a fresh breeze, 

 when she ploughs through the crests of the waves> 

 and at every roll her side is raised out of the water 

 enveloped in ruddy flames, which stream like light- 

 ning from the keel, and flash towards the surface of 

 the sea. At other times, the dolphins, while sporting 

 in the waters, trace out sparkling furrows in the 

 midst of the waves*," 



Leaving out of our consideration as inadmissible, 

 the opinion of Le Gentilf and Forster|, that the 

 light in question arises from electricity excited by the 

 friction of the water upon the sides of the advancing 

 ship, — the ascertained facts appear to be the fol- 

 lowing. There are several luminous molluscse which 

 have the faculty of emitting at pleasure a feeble 

 phosphorescent light, generally of a bluish colour., 

 Three of these have been particularized, {Nereis noc- 

 tiluca ; Medusa pelagica, /3 § ; and Monophora noc- 

 tiluca,) the latter discovered by M. Bory de St. 

 Vincent in Baudin's expedition ||. Besides these, a 



* Humboldt, Tableau de la Nature, vol. ii. p. 9, and Note. 



t Voyage aux hides, i. 685 — 98. 



J Remarks made in a Voyage round the World, p. 57. 



§Forskal, Fauna /Egyptiaco-Arabica, p. 109. 



II Voy. aux lies d'Afrique, i. 104. 



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